can be a cyst or a lipoma which is a benign fatty tumor. To confirm the diagnosis I suggest you to get it examined from your dermatologist. Till then apply warm compresses and some topical antiseptics on the bump.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.